Effects of magnetospheric activity on the current sheet energy resonance ion distribution function signature

Holland, D. L.; Bush, C. J.; Paterson, W. R.

doi:10.1029/2008ja013357

Cited by 3 publications

(4 citation statements)

References 29 publications

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“…It is natural to expect that the properties of E z vary along the geomagnetic tail; that implies a nonuniform shifting of resonant regions and subsequent steepening (or flattening) of the beamlet scaling. This effect also brings some uncertainty in the estimation of current sheet parameters made on the basis of nonadiabatic acceleration without the normal component of electric field, as it was done by Holland et al [2008].…”

Section: Discussionmentioning

confidence: 99%

“…This suggestion was experimentally verified by Chen et al [1990b] in quiet time central plasma sheet distribution functions obtained aboard ISEE‐1. Later, having used Geotail CPI data, Holland et al [2008] investigated effects of magnetospheric activity (as measured by Kp) on an ion distribution function signature of nonlinear particle dynamics in current sheet. Holland et al [2008] have used the energy resonance signature for certain values of Kp in conjunction with measurements of the magnetic field to determine a lower bound on the current sheet thickness and have found that this lower bound decreases for increasing levels of magnetospheric activity.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the electric field perpendicular to the current sheet on ion beamlets in the magnetotail

2010

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[1] Several studies, both experimental, analytical, and numerical, show that a substantial electrostatic field E z perpendicular to the magnetotail current sheet can be found. This electric field has a typical bipolar structure. We propose a theoretical analysis describing the ion behavior in the vicinity of the current sheet under the influence of E z in a two-dimensional taillike magnetic field reversal. It is shown that for some initial parameters resonant acceleration is possible, forming beamlets (small-scale and almost monoenergetic field-aligned ion beams). To check the analytical results, a test particle simulation has been performed, where the dawn-dusk electric field E y is also present to accelerate particles. We find that for electric field E z pointing away (or toward) the current sheet, the beamlet resonant regions are shifted toward the Earth (or away from the Earth) resulting in decreasing (or increasing) typical energy of ions leading to the modification of the universal scaling predicted by Zelenyi et al. (2007). Another effect due to the presence of E z is an overlapping of beamlet energies to form a wide energetic beam. Implications for beamlet observations are discussed.Citation: Dolgonosov, M. S., G. Zimbardo, and A. Greco (2010), Influence of the electric field perpendicular to the current sheet on ion beamlets in the magnetotail,

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of the electric field perpendicular to the current sheet on ion beamlets in the magnetotail

2010

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“…If we launched particles from Northern and Southern Hemisphere simultaneously, this effect eventually leads to the overlapping of even and odd resonant regions (Figures b–c). This might be important in the light of the idea of using beamlets for remote sensing of the distant magnetotail [ Holland et al , ; Kovrazhkin et al , ].…”

Section: Simulation Resultsmentioning

confidence: 99%

On the generation of ion beamlets in the magnetotail: Resonant acceleration versus stochastic acceleration

et al. 2013

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[1] In the Earth plasma sheet boundary layer, two types of ion beams (so-called beamlets of type I and of type II) were investigated for more then two decades. Type I beamlets have energies < 20 keV and small velocity dispersion, while type II beamlets have energies up to 100 keV and large velocity dispersion. It is believed that beamlets of type I result from nonadiabatic and resonant acceleration by the cross-tail electric field E y at the fulfillment of the resonant condition in the current sheet, while beamlets type II could be generated by sufficiently large level of electromagnetic fluctuations in the magnetotail. The resonant condition is very sensitive to the presence of the perturbation and eventually should be destroyed by growing "noise." We performed test particle simulation taking into account two possible acceleration mechanisms, cross-tail electric field E y and stochastic acceleration due to electromagnetic perturbations. Electromagnetic perturbation were generated by a set of oscillating clouds in the plasma sheet. We obtained that type I beamlets could be observed even in the presence of moderate levels of perturbation ıB B z (z = 0), where B z is a magnetic field component perpendicular to the current sheet plane. Increasing the perturbation level, beamlets of higher energy are obtained. The interplay of ion resonant acceleration and magnetic perturbation in the magnetotail leads to a continuous transition from beamlets of type I to beamlets of type II. A comparison of the numerical results with the observation of ion populations in magnetotail is also discussed.

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“…Numerical fits to the data show that the symmetric surface of sections have energies given by 1/4 = N + 0.6 where N is a integer. It is this variation in the symmetry properties of the surface of section and the resulting partitioning of the particles into transient and chaotic orbits that lead to the distribution function signatures that have been observed in satellite data [ Chen et al , 1990a; Holland et al , 1999, 2006, 2008]. In Figure 3, we plot the value of β c as a function of 1/4 .…”

Section: Introductionmentioning

confidence: 89%

The uncertainty dimension and fractal boundaries for charged particle dynamics in the magnetotail

et al. 2011

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[1] In this paper we examine the fractal nature of the basin boundary between forward scattered and backscattered particles as measured in the asymptotic region of the modified Harris model of the Earth magnetotail. It is shown that, in order to enter the chaotic region of phase space, an incoming ion (launched from above the midplane) must have an asymptotic pitch angle below a certain maximum value. This maximum pitch angle depends on the underlying structure of the phase space and takes on minimum (maximum) values at off-resonant (resonant) energies. Examples of the fractal basins are shown for both a resonant and off-resonant energy. Furthermore, we calculate the uncertainty exponent and the associated fractal dimension of the basin boundary as a function of the ion energy. We find that the uncertainty exponent takes on maximum (minimum) values at off-resonant (resonant) energies indicating that the box counting dimension of the basin boundary is farthest from integer values at the off-resonant energies. Finally, we show that in the integrable limit of vanishing normal component of the magnetic field, the uncertainty exponent approaches zero.Citation: Holland, D. L., M. E. Presley, R. F. Martin, and H. Matsuoka (2011), The uncertainty dimension and fractal boundaries for charged particle dynamics in the magnetotail,

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Effects of magnetospheric activity on the current sheet energy resonance ion distribution function signature

Cited by 3 publications

References 29 publications

Influence of the electric field perpendicular to the current sheet on ion beamlets in the magnetotail

Influence of the electric field perpendicular to the current sheet on ion beamlets in the magnetotail

On the generation of ion beamlets in the magnetotail: Resonant acceleration versus stochastic acceleration

The uncertainty dimension and fractal boundaries for charged particle dynamics in the magnetotail

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